The present invention relates to a tooth system for a cutter head, in particular to a tooth system for dredging cutter head.
From WO 2005/005737 A1 a tooth system is known for a tool for earth moving machinery. The tooth system is of the type comprising a holder located on the tool and a front tooth portion that is detachably arranged on and in relation to the holder. The tooth portion is in the form of an exchangeable wear and/or replacement part intended for the actual earth moving. The tooth portion has a rear leg and the holder has a cavity designed to receive the leg in interaction with the tooth portion and thereby achieve a unified joint for assimilation of occurring loads.
WO 2005/005737 A has for its purpose to achieve a new and improved tooth system for the tool for an earth removal machine. The tooth system essentially reduces or wholly eliminates the wear between the different connection parts caused by hammering and/or caused by too large surface loads on the tooth system's joint between the holder and tooth point.
WO 2005/005737 A therefore proposes a tooth system distinguished by the tooth leg and holder cavity, along at least a front part of said joint, to have a multi-armed, preferably cruciform, cross section comprising at least four projection arms and at least four grooves each that interact with each projecting arm, respectively, which projection arms comprise an, essentially vertically arranged, upper arm, an, essentially vertically arranged, lower heel and two, essentially horizontally and laterally arranged, wing portions, wherein a tensioning device is arranged at the rear part of the cavity in order to achieve adjustable pretensioning that tightens the tooth portion in relation to the holder, essentially axially along the axial symmetry axis Y of the cavity.
U.S. Pat. No. 4,932,145 A relates to a tooth point and adapter assembly for a bucket. In case of a bucket the line of action of a cutting force is more predictable than compared with a dredging head. The tooth point has an enclosed cavity for receiving the adapter mounting portion. The adapter has no cavity for receiving a mounting portion of the tooth member. As a disadvantage, the cavity being part of the tooth makes the tooth less massive and less robust and transfer of forces is at a relative small circumference. The tooth point needs to be locked against rotation opposite to that traveled during installation. This is also a disadvantage of this known tooth point and adapter assembly. To fully secure the tooth point onto the adapter, the tooth and adapter are bolted together.
US 2007/241605 A1 relates to a device for securing a shank chisel. The device has a chisel holder that has a chisel receiver for the shank chisel. The device has no cavity for “receiving the mounting portion of the tooth member”. The receiver is formed in the tooth member.
U.S. Pat. No. 4,761,900 A relates to an excavating tooth comprising an adapter and a point. As far as understood, the point is twisted onto the adapter through application of helical thread. This makes this adapter and tooth system complicate and rather vulnerable in harsh and polluting environments, like a dredging operation.
There is a need for improvement of known tooth systems in that the joint between the holder and tooth portion is even more firmly fixed.